17,028 research outputs found
Solving 1ODEs with functions
Here we present a new approach to deal with first order ordinary differential
equations (1ODEs), presenting functions. This method is an alternative to the
one we have presented in [1]. In [2], we have establish the theoretical
background to deal, in the extended Prelle-Singer approach context, with
systems of 1ODEs. In this present paper, we will apply these results in order
to produce a method that is more efficient in a great number of cases.
Directly, the solving of 1ODEs is applicable to any problem presenting
parameters to which the rate of change is related to the parameter itself.
Apart from that, the solving of 1ODEs can be a part of larger mathematical
processes vital to dealing with many problems.Comment: 31 page
Public Health England's recovery tools: potential teaching resources?
The file attached to this record is the author's final peer reviewed version.Training to combat chemical and radiation accidents, incidents or attacks is critical for health professionals
due to recent events involving these hazards or their use as unconventional weapons, such as the use of
the nerve agent novichok in Salisbury, UK. Health professionals need to have appropriate knowledge and
skills to effectively respond to future events involving any of these substances, which requires a rapid and
coordinated response from different professionals to protect the environment and minimise the number of
people exposed and reduce morbidity and mortality. However, despite chemical and radiation incidents
becoming increasingly prevalent, literature reviews have shown that there is a lack of teaching of
appropriate competences to face future crises in Europe, particularly amongst clinicians and other health
professionals that would be part of the initial response. Thus, De Montfort University (DMU, UK) in
collaboration with different academics from the University of Alcalá (Spain) and researchers from Public
Health England (PHE) with comprehensive experience in environmental decontamination and restoration,
have created a short training course for providing undergraduate/postgraduate students with basic skills
to respond to chemical incidents, basic skills that are based on the major competences recently identified
by the European Commission [1]. This novel training has been tested with students from different
backgrounds in various European universities, recording high degrees of acquisition of the various basic
competences that we developed to initially respond to chemical events [2]. To develop the practical part
of this chemical training, we have incorporated the novel guidance and methodology developed by PHE
to successfully tailor a protection and recovery response to any incident involving chemical substances,
which is available in the “UK Recovery Handbook for Chemical Incidents” [3] and its web-based tools:
“Chemical Recovery Navigation Tool” (CRNT, [4]) and “Chemical Recovery Record Form” (CRRF, [5]).
These innovative resources aid the user to select effective protection, decontamination and restoration
techniques or strategies from a pool of up-to-date options applicable to different environments according
to the physicochemical properties of the chemical(s) involved and the area affected. The CRNT is
accompanied by the CRRF, which facilitates collection and analysis of the necessary data to inform
decisions, and an e-learning resource named “Chemical Recovery: Background” (CRB, [6]), which could
facilitate the learning of environmental decontamination and restoration. We are currently developing a
short training course to cover minor radiation incidents; this radiation training will follow the same methods
used to develop the chemical training, but with the specific PHE recovery tools to tackle such events,
specifically the “UK Recovery Handbooks for Radiation Incidents” [7] and its associated web-based tools
“Radiation Recovery Navigation Tool” (Rad RNT, [8]), one for each environment: food production systems,
inhabited areas and drinking water supplies. This communication will explore the use of the PHE’s
Recovery Navigation Tools as potential resources to facilitate the acquisition of basic knowledge to tailor
protection and recovery interventions for minor chemical and radiation incidents to protect the public
Clone size distributions in networks of genetic similarity
We build networks of genetic similarity in which the nodes are organisms
sampled from biological populations. The procedure is illustrated by
constructing networks from genetic data of a marine clonal plant. An important
feature in the networks is the presence of clone subgraphs, i.e. sets of
organisms with identical genotype forming clones. As a first step to understand
the dynamics that has shaped these networks, we point up a relationship between
a particular degree distribution and the clone size distribution in the
populations. We construct a dynamical model for the population dynamics,
focussing on the dynamics of the clones, and solve it for the required
distributions. Scale free and exponentially decaying forms are obtained
depending on parameter values, the first type being obtained when clonal growth
is the dominant process. Average distributions are dominated by the power law
behavior presented by the fastest replicating populations.Comment: 17 pages, 4 figures. One figure improved and other minor changes. To
appear in Physica
Superstatistical fluctuations in time series: Applications to share-price dynamics and turbulence
We report a general technique to study a given experimental time series with
superstatistics. Crucial for the applicability of the superstatistics concept
is the existence of a parameter that fluctuates on a large time scale
as compared to the other time scales of the complex system under consideration.
The proposed method extracts the main superstatistical parameters out of a
given data set and examines the validity of the superstatistical model
assumptions. We test the method thoroughly with surrogate data sets. Then the
applicability of the superstatistical approach is illustrated using real
experimental data. We study two examples, velocity time series measured in
turbulent Taylor-Couette flows and time series of log returns of the closing
prices of some stock market indices
A Method to Tackle First Order Differential Equations with Liouvillian Functions in the Solution - II
We present a semi-decision procedure to tackle first order differential
equations, with Liouvillian functions in the solution (LFOODEs). As in the case
of the Prelle-Singer procedure, this method is based on the knowledge of the
integrating factor structure.Comment: 11 pages, late
Axial gravity, massless fermions and trace anomalies
This article deals with two main topics. One is odd parity trace anomalies in
Weyl fermion theories in a 4d curved background, the second is the introduction
of axial gravity. The motivation for reconsidering the former is to clarify the
theoretical background underlying the approach and complete the calculation of
the anomaly. The reference is in particular to the difference between Weyl and
massless Majorana fermions and to the possible contributions from tadpole and
seagull terms in the Feynman diagram approach. A first, basic, result of this
paper is that a more thorough treatment, taking account of such additional
terms { and using dimensional regularization}, confirms the earlier result. The
introduction of an axial symmetric tensor besides the usual gravitational
metric is instrumental to a different derivation of the same result using Dirac
fermions, which are coupled not only to the usual metric but also to the
additional axial tensor. The action of Majorana and Weyl fermions can be
obtained in two different limits of such a general configuration. The results
obtained in this way confirm the previously obtained ones.Comment: 55 pages, comments added in section 2 and 5. Sections 6.4, 6.6, 7,
7.1, 7.2 and Appendices 5.3, 5.5 partially modifie
Massive 70 micron quiet clumps I: evidence of embedded low/intermediate-mass star formation activity
Massive clumps, prior to the formation of any visible protostars, are the
best candidates to search for the elusive massive starless cores. In this work
we investigate the dust and gas properties of massive clumps selected to be 70
micron quiet, therefore good starless candidates. Our sample of 18 clumps has
masses 300 < M < 3000 M_sun, radius 0.54 < R < 1.00 pc, surface densities Sigma
> 0.05 g cm^-2 and luminosity/mass ratio L/M < 0.3. We show that half of these
70 micron quiet clumps embed faint 24 micron sources. Comparison with GLIMPSE
counterparts shows that 5 clumps embed young stars of intermediate stellar mass
up to ~5.5 M_sun. We study the clump dynamics with observations of N2H+ (1-0),
HNC (1-0) and HCO+ (1-0) made with the IRAM 30m telescope. Seven clumps have
blue-shifted spectra compatible with infall signatures, for which we estimate a
mass accretion rate 0.04 < M_dot < 2.0 x 10^-3 M_sun yr^-1, comparable with
values found in high-mass protostellar regions, and free-fall time of the order
of t_ff = 3 x 10^5 yr. The only appreciable difference we find between objects
with and without embedded 24 micron sources is that the infall rate appears to
increase from 24 micron dark to 24 micron bright objects. We conclude that all
70 micron quiet objects have similar properties on clump scales, independently
of the presence of an embedded protostar. Based on our data we speculate that
the majority, if not all of these clumps may already embed faint, low-mass
protostellar cores. If these clumps are to form massive stars, this must occur
after the formation of these lower mass stars.Comment: 44 pages, 11 Figures. Accepted for publication in MNRA
Healthrisk assessment from exposure to trihalomethanes in drinking water
A aplicação de compostos clorados na desinfeção da água pode induzir à formação de subprodutos da desinfeção (SPD) com efeitos carcinogénicos e mutagénicos comprovados. Neste trabalho, apresenta-se uma síntese de um estudo sobre a ocorrência de trihalometanos (THM) na água de abastecimento, realizado nos catorze municípios do distrito de Braga (Portugal), visando a avaliação do risco de cancro (RC) e de efeitos não carcinogénicos (HI) com base na metodologia desenvolvida pela USEPA e IRIS. Num cenário gravoso, correspondente à prevalência da maior concentração de THM detetada no período monitorizado, o indicador RC daria valores superiores ao limite máximo definido como negligenciável, verificando-se ser a ingestão a via de exposição mais relevante. Os resultados obtidos para o indicador HI foram quase sempre inferiores à unidade, indicando um nível de risco aceitável, de acordo com os pressupostos do método utilizado. O uso de indicadores do risco para a saúde constitui uma ferramenta útil quer no apoio à decisão das entidades gestoras de sistemas de abastecimento de água, quer na definição de estratégias e políticas de saúde pública que visem a mitigação deste risco.Chlorination havebroughtenormous benefits to the preservation of public health as a low-cost disinfection method, but it cangenerate severalhalogenated organic compounds,as disinfection by-products (DBP), with potentialand proven carcinogenic and mutagenic effects. This workpresents a synthesis of the study performed in watersupply systems ofthe fourteen municipalities of Braga district (Portugal), aiming at the evaluation of lifetime cancer risk (CRindex),and the risk of non-carcinogenic effects (HI-Hazard Index) fromexposure to THMs, usingamethod proposed by USEPA and IRIS.In a severescenario, corresponding to the prevalence of maximum THMconcentrationoccurred duringthe monitored period, the CR index would achieve valueshigher than the maximum limit defined asnegligible forall these municipalities. The HI indexresultswereoftenlower than one,which is consideredas an acceptable risk level. The use of health risk indicators can be a useful tool both in supporting the decision-making of water supplyutilitiesandin the definition of public health strategies/policies forrisk mitigation in order to increasethe life quality and the wellnessof populations
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